Thienyl mercaptals and mercaptols



Patented June 17, 1952 2,600,838 THIENYL MERCAPTALS AND MERCAPTOLS John W. Brooks, Wenonah, N. J., assignor to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Original application November 26, 1947, Serial No. 788,330. Divided and this application November 19, 1948, Serial No. 61,121

p This invention relates to a group of new chem-- the manner in which oxidation manifests itself within the oil vary with the type and degree of refinement to which the oil has been subjected and with the conditions under which it is used or tested; that is, the products formed in an oil fraction as a result of oxidation and the degree to which they are formed depend on the extent to which the various unstable constituents, or constituents which may act as oxidation catalysts, have been removed by refining operations and also upon the conditions of use.

The present invention is predicated upon the discovery that a new group of chemical compounds, the thienyl mercaptals and mercaptols, greatly improve the oxidation characteristics of mineral oil fractions by the incorporation therein of minor proportions of these compounds. It has been found that by the addition of a thienyl mercaptal or thienyl mercaptol to a viscous mineral oil fraction, the development of undesirable products and properties, such as acid, sludge, discoloration, and corrosiveness toward alloybearing metals normally encountered under conditions of use has been substantially inhibited.

The compounds of this invention may be designated by the general formula:

S--i -S Thus, the above compounds include the thienyl mercaptols and thienyl mercaptals.

6 Claims. (01. 260-329),

action of an aldehyde or ketone on a thiophenethiol in the presence of anhydrous hydrogen chloride or similar condensation catalyst. Under such conditions, the hydrogen of the mercapto group in the thiophenethiol reacts with oxygen of the carbonyl-containing aldehyde or ketone employed to split out water and to yield the desired thienyl mercaptal or thienyl mercaptol. In general, the temperature at which the above reaction is carried out will be between about 0 C. and about 100 C. and preferably between about 0 C. and about 30 C. It will be understood that the particular conditions of temperature employed will depend in part on the nature of the aldehyde or ketone reactant used. The thiophenethiol reactant above-mentioned may be prepared by any one of numerous procedures heretofore described in the literature. Thus, 3-thiophenethiol may be produced by the process described in Chem. Inds. 60, 593-5, 620 (1947) and 2-thiophenethiol by the procedure described in Ber. Dtsch. Chem. Ges. 19, 1615 (1886) or in Ber. Dtsch. Chem. Ges. 20, 1756 (1887).

Any of the commonly employed catalysts'useful in efiecting reaction between a mercaptan and an aldehyde or ketone are contemplated for use in promoting the reaction of thiophenethiol with an aldehyde or ketone. Thus, while the above mentioned anhydrous hydrogen'chloride is preferably used as the condensation catalyst herein, various other materials such as calcium chloride. boron trifluoride, zinc chloride, ferric chloride, ammonium chloride, and the like, may be used.

The above described reactions will usually be carried out with a molar ratio of thiophenethiol to aldehyde or ketone of about 2:1 in order The thienyl mercaptols and mercaptals described above may' suitably be prepared by the to obtain the desired thienyl mercaptal or thienyl mercaptol. p The nature of the alkyl, aryl, aralkyl, or heterocyclic group or groups present in the thienyl mercaptals and mercaptols described herein may be either saturated or unsaturated and may contain various substituents such as those introduced by halogenation, nitration, alkylation, sulfonation, and the like. The alkyl or aralkyl groups may be either straight chained, branch chained, monocyclic or polycyclic, and may contain one or more aromatic groups. Representative of the alkyl, aralkyl, aryl, and heterocyclic thienyl mercaptals and mercaptols of this invention, are those produced upon reacting thicphenethiol with aldehydes, such as acetaldehyde, benzaldehyde, furfural, thiophene aldehyde, crotonaldehyde, cinnamaldehyde, salicylaldehyde, chloral, aldol, acrolein, etc., or those produced upon reacting thiophenethiol with ketones, such as benzophenone, acetone, acetothienone, acetophenone, methyl ethyl ketone, methyl vinyl ketone, diacetone alcohol, etc. This list, of course, is not to be construed as limiting since th pn sentin e n con em l es t e use of alley-1, aryl, aralkyl, and heterocyclic aldehydes or ketones generally as reactants to synthesize the compounds of this invention. Those skilled in the art will readily -recogni;ze-va r igus other aldehydes or ketones which may be employed according to the aboueldescribedprocee dure in preparing the compounds or this invention.

The thiophenethiol reactant emplgyegl syn-.-

thesizing the compounds of thisinventign gray-be either a Z-thiophenethiol .or a BrtlliQIihfihfifihiQl and may contain one or more substituentgroups, such as alkyl, alkoxy, halogen, nitro; or acyl groups. The preparation of the compounds of themesent invention may be illustrated bythe following examples, which are given by way of illustration and not intended to be a limitation on the scope of the invention.

Prcramzrnof utyrcldehyde. di-i-rluezw mercc id Tw 1-1 irtwtwc grams (21 10 2 cl: .3- thiophenethiol and 72 grams (1 mule) o f butyra ldehyde were mixed. Upon'mixin the tre-Imperature roseto about 75 The mixt re, o t-reactants was cooled to a temperature .of 15 by an ice bath, and anhydrous hydrogen chloride was then, bubbled into the mixture for ;a pc 'od of 2 hours. At the end of this time, theaddihc of hydrogen chloride was stopped and the reaction mixture was cooled overnight. The reaction product so obtained was then poured into ice water, washed with water, dried over anhydrous magnesium sulfate and distilled under reduced pressure. One hundred .sixty-fiye grams (58 per cent yield) of :butyraldehyde, d1i 3rthieny1 mercaptal were distilled from the reactiQll m xture at a temperature .01? 17.31176 (3. under 2 millimeters pressure. The sulfur analysis of this compound was 44.47 per cent, the theoretical sulfur content being 44316 per cent. This ppmpcund is hereinafter referred to 5 cc nncund Prepgzration of acetone, di-B' -thienyZ merccptol Two hu d ed thi ty-a e grams 2 .mcles) c13- thiophenethiol and 58 grams (1 mole) of ,acetpne we mi e A hyd u h drog n chloride wa passed into th mixtu e c reactants m n aine at a tempe etur-ecf 0 until the. mixtu e. wa saturated w th iliyd csen chlcride The resultins mixture was c ed eve ni ht and the wash d with col w e dr ed eve enh d icu magne iu sulfa nd stil ed u der reduce p es u TW undred thi ty-th ee grains (8 er c t y e d o ace one, ith. c. i me ce to w redistilled r m t e eaetiq m xtu a elem- Perature of 121 115? un r n mi l mete pr ssu T1l..$l .l nalys s cf thi c mman was 46.9 per cent, the theoretical sulfur content 4 being 47.06 per cent. This compound is hereinafter referred to as compound II.

EXAMPLE III Preparation of benzaldehyde, di-3-thienyl mercaptal -r eacti0n Eroductso obtained was washed well withjce water to remove hydrogen chloride, dried over anhydrous magnesium sulfate and topped to p temperel'ullie-df' 100 C. under a pressure of one millimeter. Three hundred fifty-two grams (73 -.per cent yield) of benzaldehyde, di-3-thienyl Inercaptal were obtained as a residue. The sulfur analysis of this compound was 39.05 per cent, the theoretical sulfur content being 40.0 per cent. This compound is hereinafter referred to as compound II Preparation of benzophenone. .di-3'-.thienyl merc r c Three hundred sixty-five grams (Z-moles) of benzqphenone and 400 cc. of xylene-were mixed and copled t9 atemperature offi10 (3. Four hundred sixty-four grams (4 moles) of fi-thiophenethiol wereadded to the mixture. Anhydrous hydrogen chloride was then passed through the resulting mixture for a period of ;2 hours. The reaction mixture-was thereafter maintained in a ccgl place overnight. Six hundred thirty grams percent yield) of benzophenone, vdi-3-thieny1 r nercaptol were formed as a solid. This material was l ecrystallized several times from cyclohexane ,tc yield white c y e in a meltin pointqf l 5 2 C The sulfur analysis of this compound was 32.1 6 per cent, the'theoretical sulfur content being 32,35 per cent. This compound is he einaf er referred t as ccmpound' v- EXAMPLE V Riche -mime .Qf hydmcinnamaldehyde, 11M- thie y mercuric/l dirty-sev n grams /e. 1. 9 c 'hydrecinnemaldehydc and 3. .9 .cc- .9; tcluene we e mixed and he. mixtu e ccclesi to a t mperatu e 131. Q hu dr d ,t c efive grams /4 moles.) cf B-t cPlien hiQl ere ad d o e ocleds lut cn- Anh drous h d og n chlor de was then u ble into the result n mix ure for a period o 2 hcurs, t the end c th s-time. the addition of hydr chloride st pped and the r ac ion mixture was cooled overnight. The reaction product was washed Well with Water to remove hydrogen chloride, dried over anhydrous calcium sulfate and topped to a temperature of C. under a pressure of one millimeter. One hundred twenty-one grams (69.5 per cent yield) of hydrocinna-ma'ldehyde, di-3-thienyl mercaptal were obtained as a residue. The sulfur analysis of this compound was 34.96 per cent, the theoretical sulfur content being 36;78 per cent. This cempound is h rei eit r fe to as compound -V.'

. rind of 35 minutes.

.cal compounds.

EXAMPLE v1 Preparation of jm'furaldehyde, di-3'-thieny'l mercaptal Two hundred thirty-two grams (2 moles) of 3- thiophenethiol and 76 grams (1 mole) of furfuraldehyde were placed in a flask maintained at a temperature of 8 C. Anhydrous hydrogen chloridewas'bubbled into this mixture for a pe- The reaction product resulting was washed with ice water, dried over anhydrous magnesium sulfate and topped to a temperature of 100 C. under a pressure of one millimeter. Furfuraldehyde, di-3-thienyl mercaptal was obtained as a residue in 80 per cent yield. The sulfur analysis of this compound was 41.3 per' cent, the theoretical sulfur'content bemg 41.3 per cent. This compound is hereinafter referred to as compound VI.

EXAMPLE v11 Preparation ofacetothienone, di-E-thieniyl mercaptol Three hundred seventy-eight grams (3 moles) of acetothienone and 696 grams (6 moles) of 3- thiophenethiol were placed in a flask maintained.

ing 47.06 per cent. This compound is hereinafter referred to as compound VII.

The dithienyl mercaptals and mercaptols of this invention are contemplated for use as intermediates in ,the preparation of pharmaceuticals, insecticides, and in the synthesis of other chemi- They have been found to be particularly valuable, however, as additives in the stabilization of petroleum oil fractions in inhibiting the development of those undesirable products and properties, such as acid, sludge, discoloration, and corrosiveness, toward alloy-bearing metals normally encountered under conditions of use. Thus, it is well known that motor oils, especially those refined by certain solvent extraction methods, tend to oxidize when sub mitted to high temperatures and to form products that are corrosive to metal bearings. corrosive action may be quite severe with certain bearings, such as those having the corrosion susceptibility of cadmium-silver alloys, and may cause their failure within a comparatively short time. The following test was used to determine the corrosive action of a motor oil on an automobile rod bearing.

The oil used consisted of Pennsylvania neutral and residuum stocks separately refined by means of chlorex and then blended to give an S. "!notor oil with a specific gravity of 0.872, a flash point of 435 F. and a Saybolt Universal viscosity of about 318 seconds at 100 F. The oil was tested by adding about a G-gram section of a bearing containing a cadmium-silver alloy surface and heating it to 175 C. for 22 hours while a stream of air was bubbled against the surface of the bearing. The loss in weight of the bearing during this treatment measures This Concentration in Per Cent Mg. Loss Compound Added in Weight A second test, to which an 011 containing a minor proportion of the compounds of this in- 25 vention was subjected, consisted essentially of passing oxygen through a sample of a highly refined oil which had been prepared by treating a petroleum distillate with 40 pounds of 98 per cent sulfuric acid and 180 pounds of 103 per cent oleum per barrel of distillate, followed by a clay percolation. The oil so treated had a specific gravity of 0.871, a flash point of 310F. and a viscosity (S. U. V.) of 69 seconds at 100 F. Oxygen was bubbled through a 150-gram sample of the above oil at a rate of 2 liters per hour for a period of 70 hours, at a temperature of 120 C. The neutralization number of the oil was measured at the end of the test by titration with alcoholic potash. In this test, the base oil containing no additive developed a neutralization number of about 18. The following data indicate that the compounds of this invention are effective in inhibiting the development of acidity in a mineral oil when the same is subjected to oxidation conditions, as evidenced by the comparatively low neutralization number of such oils at the completion of the above test. In each of the oils tested, 0.1 per cent by weight of a compound of this invention was incorporated therein.

Compound Added 99999. 9 0 O asses-2...

From the foregoing test results, it will be evident that thienyl mercaptals and mercaptols of this invention are effective stabilizing agents for petroleum lubricating oil fractions. The quantity of compound employed as stabilizer to inhibit the undesirable effects of oxidation in the oil may be varied, depending upon the character of the oil and the severity of the conditions to which it is exposed. Ordinarily, the compositions will be added to mineral oil fractions in an amount ranging from about 0.1 per cent to about 5 per cent, but may be added in amounts up to 10 percent by weight in some instances. An additional illustration of the effectiveness of the above stated minor proportions of thienyl mero accuses capitals-and mercaptolsininhibiting the. tendency of oils to cozrodezmetalhearings is shown by the iollowing comparative testz-resultszin-which a blank oil. and an. oil; containing minor proportions oi! the compounds of this invention were "subjected to aLauson engine test. In'this test. a single cylinder Lauson engine wasrun at" a "speedof 1825 R. P. M. with an oil temperature 01-27UPF. and a jacket temperature of 212" F. The oil used was an SAE. 20 motor. oil having a kinematic viscosity of 8.6 at 210 F. The neutralization number and the percentage viscosity increase of the oil and oil blends and the extent of corrosion as measured by the loss in weightof the copper-lead hearings were determined atter 100 hours. The results are set forth in the table below:

Average weight loss of top and bottom ,5 bearings.

It will beobserved from the foregoingexamples and. the results set forth that the thienyl. mercaptalsand mercaptols of this invention are uni formly. effective in inhibiting the deleterious effects. of oxidation on viscous mineral oil fractions which have. been subjected to'the' various methods of refining treatment currently used. In other words, these compounds are effective as inhibitors in highly refined oils, moderately refined oils, and solvent refined oils.

It is to be understood that the examples, procedures and oil compositions described above are illustrative only and are not to be construed as limiting the scope of this invention thereto.

Thus, in. addition to the specific compounds set forth, other thienyl mercaptals or mercaptols '8 falling within the scope of the above disclosed general formula may similarly be employed as additives in improving thepropertiesof viscous mineral oil fractions normally subject to deterioration under oxidizing conditions.

This application is a division of co-pending application Serial No. 788,330, filed November 26, 1947, now U. S. 2,480,831 issued September 6, 1949.

I claim:

1. Asa new composition of matter, the compound having the general formula:

U if lj where R1 isLa substituent selected .from thegroup consistingof hydrogen anda methyl group; and R2 is a substituent selectedfromithe group consisting of methyl, propyl, phenyl, phenethyl, furyl, and thienyl groups.

2. As a new composition of matter, butyraldehyde, di-B-thienyl mercaptal.

3. As a new composition of matter, acetone, di- S-thienyl mercaptol.

4. As a new composition of matter, benzaldehyde, di-B-thienyl mercaptal.

5. As a new composition of matter, benzophenone, di-3-thieny1 mercaptol.

6. As a new composition of matter, acetothienone, .di-3 -thienyl; mercaptol.

JOHN W. BROOKS.

REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 2,229,665 Mochel -Jan. 28, 1941 2,480,831. Brooks Sept. 6, 1949 OTHER REFERENCES Whitmore: Organic Chemistry," p. 893, You Nostrand, N. Y., 1937.

Richter: Organic Chemistry," pp. 649-650, Wiley, N. Y., 1938. 

1. AS A NEW COMPOSITION OF MATTER, THE COMPOUND HAVING THE GENERAL FORMULA: 